Fuel grade for V12V
Discussion
I've had some interesting conversations on this topic with my father who's a petrochemical engineer. He's been doing this for 42 years (originally starting for ICI - proper old school). His qualified opinion is that regardless of knock sensors (and it took a lot of crayons and puppets to get him to understand this), higher octane fuel (specifically things like shell ultimate) are generally a much better fuel. This is because of the way the fuel is produced. Premium fuels are produced via a process to liquify gas rather than refine oil. As a result, they're very much cleaner and over the duration, have a huge impact on engine cleanliness. One caveat he did state, is that modern engines are much more robust than they once were - meaning that it shouldn't really make a difference to engine life and wear. Perhaps if people ran cars into the hundreds of thousands of miles that modern engines are capable of, you'd see a benefit. But, we're in an age where people view a car with 100,000 miles as 'old', so with a life cycle of this duration, you won't see a difference.
In summary, if you have a car that you're running to be a future classic, then use premium fuel. If you're going ditch it when it gets to 100,000 miles, then don't bother.
So there you have it. From an old school bloke called Ken.
In summary, if you have a car that you're running to be a future classic, then use premium fuel. If you're going ditch it when it gets to 100,000 miles, then don't bother.
So there you have it. From an old school bloke called Ken.
roughrider]If you're going to be driving it hard [track day said:
its best to use Super unleaded just to rule out any chance of pinking/detonation.
Sorry but that's just wrong - please see either Grants post above or read the BR sticky thread. The V12V engine has no knock sensor and has fixed timing for 95 octane fuel, so there is zero chance of pinking or pinking being reduced by using super over regular unleaded. As noted above there is a slight benefit in the fuels like v-power have good cleaning agents, but you can find these too in good quality regular unleaded.The V12VS engine is a different case however, as one of the main improvements in over the old 510bhp V12V engine was the introduction of a knock sensor to enable the use and benefit of super unleaded.
The octane rating also refers to the rate the flame front travels through the fuel. The higher the rating the slower the travel. Instead of getting a bang you get a baaaaaaaaaang this mens the fuel is powering the piston for a greater length on the down stroke so you do actually get more power. I always use the highest octane rated fuel.
You are talking about my bag here chaps, paid for 20+years by many brands to develop power from petrol engines, there are many misconceptions.
Filling with higher octane fuel does not mean addition of hydrocarbon content of influencing type, or oxygen, to mean the engine develops different power across the octane ratings if all other variables are kept the same (spark, fuel, compression ratio).
Octane number is only a measure of whatever fuel blend is used, tendency to burn in a controlled manner (the higher the rating) as opposed exploding in an uncontrolled manner when compressed (the lower the rating / detonation). However, a much lower octane rating requires retarded spark to combat detonation (looming engine failure) which would mean power reduction, but the varying power is always related to spark.
If an engine with no knock control was mapped on 95 (the V12 we talk about here), then it will safely run all day long on 95, have no power gain if 100 was used, but likely hole a piston if 90 was used because it has no means to retard spark. But if 90 was used, more-or-less at the same ignition timing (if the engine could run long enough before failing) the power would be the same as on 95.
The reason retarded spark combats detonation is because combustion is earlier in compression cycle, not giving the chance for combustion gas to build pressure / volatility so combats uncontrolled explosion, but in process returns less power from burn above piston versus a more volatile burn from higher charged / higher octane fuel at more advanced spark which allows more compression of mixture.
Meaning in terms of power output - its all about spark angle, less about the fuel grade in isolation. Perhaps here the misconceptions stem from fuel companies who would stand to gain?
There is only one reason why the comment to run higher octane fuel on track days is valid. It is due to the tendency of the more thrashed engine to pull over oil in breather system. Oil mixed into petrol lowers the octane rating. But on the V12 engine unless it had been apart before for a fix, and the heads were skimmed so compression ratio higher, it is unlikely ever to detonate on 95 octane to a level which causes failure. But i would guess most folk regardless of this would fill with highest octane possible for track day just for reassurance factor. Some would say its because of higher air charge temps, meaning with a fixed spark angle the higher fuel octane combats detonation. Not true, on seeing higher charge temps the EMS will back out spark, it doesn't need knock sensors for that.
On the subject of a branded fuel versus supermarket. Dont all tankers get filled up by the same nozzle at the handful of fuel depots, meaning the only differentiation is whatever the treatments go in on top afterwards? Again, misconception where fuel companies stand to gain.
Filling with higher octane fuel does not mean addition of hydrocarbon content of influencing type, or oxygen, to mean the engine develops different power across the octane ratings if all other variables are kept the same (spark, fuel, compression ratio).
Octane number is only a measure of whatever fuel blend is used, tendency to burn in a controlled manner (the higher the rating) as opposed exploding in an uncontrolled manner when compressed (the lower the rating / detonation). However, a much lower octane rating requires retarded spark to combat detonation (looming engine failure) which would mean power reduction, but the varying power is always related to spark.
If an engine with no knock control was mapped on 95 (the V12 we talk about here), then it will safely run all day long on 95, have no power gain if 100 was used, but likely hole a piston if 90 was used because it has no means to retard spark. But if 90 was used, more-or-less at the same ignition timing (if the engine could run long enough before failing) the power would be the same as on 95.
The reason retarded spark combats detonation is because combustion is earlier in compression cycle, not giving the chance for combustion gas to build pressure / volatility so combats uncontrolled explosion, but in process returns less power from burn above piston versus a more volatile burn from higher charged / higher octane fuel at more advanced spark which allows more compression of mixture.
Meaning in terms of power output - its all about spark angle, less about the fuel grade in isolation. Perhaps here the misconceptions stem from fuel companies who would stand to gain?
There is only one reason why the comment to run higher octane fuel on track days is valid. It is due to the tendency of the more thrashed engine to pull over oil in breather system. Oil mixed into petrol lowers the octane rating. But on the V12 engine unless it had been apart before for a fix, and the heads were skimmed so compression ratio higher, it is unlikely ever to detonate on 95 octane to a level which causes failure. But i would guess most folk regardless of this would fill with highest octane possible for track day just for reassurance factor. Some would say its because of higher air charge temps, meaning with a fixed spark angle the higher fuel octane combats detonation. Not true, on seeing higher charge temps the EMS will back out spark, it doesn't need knock sensors for that.
On the subject of a branded fuel versus supermarket. Dont all tankers get filled up by the same nozzle at the handful of fuel depots, meaning the only differentiation is whatever the treatments go in on top afterwards? Again, misconception where fuel companies stand to gain.
BamfordMike said:
You are talking about my bag here chaps, paid for 20+years by many brands to develop power from petrol engines, there are many misconceptions.
Filling with higher octane fuel does not mean addition of hydrocarbon content of influencing type, or oxygen, to mean the engine develops different power across the octane ratings if all other variables are kept the same (spark, fuel, compression ratio).
Octane number is only a measure of whatever fuel blend is used, tendency to burn in a controlled manner (the higher the rating) as opposed exploding in an uncontrolled manner when compressed (the lower the rating / detonation). However, a much lower octane rating requires retarded spark to combat detonation (looming engine failure) which would mean power reduction, but the varying power is always related to spark.
If an engine with no knock control was mapped on 95 (the V12 we talk about here), then it will safely run all day long on 95, have no power gain if 100 was used, but likely hole a piston if 90 was used because it has no means to retard spark. But if 90 was used, more-or-less at the same ignition timing (if the engine could run long enough before failing) the power would be the same as on 95.
The reason retarded spark combats detonation is because combustion is earlier in compression cycle, not giving the chance for combustion gas to build pressure / volatility so combats uncontrolled explosion, but in process returns less power from burn above piston versus a more volatile burn from higher charged / higher octane fuel at more advanced spark which allows more compression of mixture.
Meaning in terms of power output - its all about spark angle, less about the fuel grade in isolation. Perhaps here the misconceptions stem from fuel companies who would stand to gain?
There is only one reason why the comment to run higher octane fuel on track days is valid. It is due to the tendency of the more thrashed engine to pull over oil in breather system. Oil mixed into petrol lowers the octane rating. But on the V12 engine unless it had been apart before for a fix, and the heads were skimmed so compression ratio higher, it is unlikely ever to detonate on 95 octane to a level which causes failure. But i would guess most folk regardless of this would fill with highest octane possible for track day just for reassurance factor. Some would say its because of higher air charge temps, meaning with a fixed spark angle the higher fuel octane combats detonation. Not true, on seeing higher charge temps the EMS will back out spark, it doesn't need knock sensors for that.
On the subject of a branded fuel versus supermarket. Dont all tankers get filled up by the same nozzle at the handful of fuel depots, meaning the only differentiation is whatever the treatments go in on top afterwards? Again, misconception where fuel companies stand to gain.
Filling with higher octane fuel does not mean addition of hydrocarbon content of influencing type, or oxygen, to mean the engine develops different power across the octane ratings if all other variables are kept the same (spark, fuel, compression ratio).
Octane number is only a measure of whatever fuel blend is used, tendency to burn in a controlled manner (the higher the rating) as opposed exploding in an uncontrolled manner when compressed (the lower the rating / detonation). However, a much lower octane rating requires retarded spark to combat detonation (looming engine failure) which would mean power reduction, but the varying power is always related to spark.
If an engine with no knock control was mapped on 95 (the V12 we talk about here), then it will safely run all day long on 95, have no power gain if 100 was used, but likely hole a piston if 90 was used because it has no means to retard spark. But if 90 was used, more-or-less at the same ignition timing (if the engine could run long enough before failing) the power would be the same as on 95.
The reason retarded spark combats detonation is because combustion is earlier in compression cycle, not giving the chance for combustion gas to build pressure / volatility so combats uncontrolled explosion, but in process returns less power from burn above piston versus a more volatile burn from higher charged / higher octane fuel at more advanced spark which allows more compression of mixture.
Meaning in terms of power output - its all about spark angle, less about the fuel grade in isolation. Perhaps here the misconceptions stem from fuel companies who would stand to gain?
There is only one reason why the comment to run higher octane fuel on track days is valid. It is due to the tendency of the more thrashed engine to pull over oil in breather system. Oil mixed into petrol lowers the octane rating. But on the V12 engine unless it had been apart before for a fix, and the heads were skimmed so compression ratio higher, it is unlikely ever to detonate on 95 octane to a level which causes failure. But i would guess most folk regardless of this would fill with highest octane possible for track day just for reassurance factor. Some would say its because of higher air charge temps, meaning with a fixed spark angle the higher fuel octane combats detonation. Not true, on seeing higher charge temps the EMS will back out spark, it doesn't need knock sensors for that.
On the subject of a branded fuel versus supermarket. Dont all tankers get filled up by the same nozzle at the handful of fuel depots, meaning the only differentiation is whatever the treatments go in on top afterwards? Again, misconception where fuel companies stand to gain.
Edited by AMDBSNick on Sunday 14th December 09:22
woodsypedia said:
In summary, if you have a car that you're running to be a future classic, then use premium fuel. If you're going ditch it when it gets to 100,000 miles, then don't bother.
So there you have it. From an old school bloke called Ken.
thanks for the input and I'm sure ken is a thoroughly nice chap, but that statement is plain wrong. I wont answer the question for you, but what are the key factors that mean, say, at 150k miles the supermarket fuel engine is game over versus premium fuel engine still as fresh as a daisy??? We are not in days of two stroke or an A series mini which needed a de coke every 5 hours.So there you have it. From an old school bloke called Ken.
BamfordMike said:
On the subject of a branded fuel versus supermarket. Dont all tankers get filled up by the same nozzle at the handful of fuel depots, meaning the only differentiation is whatever the treatments go in on top afterwards? Again, misconception where fuel companies stand to gain.
NopeBigScotty said:
Nope
you are telling me nope to something, albeit in the past, i have seen with my own eyes.worth a read
http://www.pistonheads.com/gassing/topic.asp?t=989...
Edited by BamfordMike on Sunday 14th December 00:07
BamfordMike said:
you are telling me nope to something, albeit in the past, i have seen with my own eyes.
worth a read
http://www.pistonheads.com/gassing/topic.asp?t=989...
I'm able to tell you nope, as I work at the places that fill the tankers up. worth a read
http://www.pistonheads.com/gassing/topic.asp?t=989...
Edited by BamfordMike on Sunday 14th December 00:07
"According to the Petrol Retailers' Association, there is no difference between the standard petrol and diesel that you buy from either a franchised fuel station or a supermarket forecourt. In many cases, the fuel is sourced from the same refineries and sometimes delivered in the same tankers.
Supermarkets are prepared to sell their fuel at very little or almost no profit in order to tempt shoppers into the supermarket. The theory is that shoppers will think that if it sells cheap fuel, it'll also sell cheap food.
The difference in fuels is in specialist or premium fuels, such as Shell Optimax and BP Ultimate, which contain additives to improve performance and efficiency. When you buy these fuels, you pay for the special ingredients."
What Car 2005
Supermarkets are prepared to sell their fuel at very little or almost no profit in order to tempt shoppers into the supermarket. The theory is that shoppers will think that if it sells cheap fuel, it'll also sell cheap food.
The difference in fuels is in specialist or premium fuels, such as Shell Optimax and BP Ultimate, which contain additives to improve performance and efficiency. When you buy these fuels, you pay for the special ingredients."
What Car 2005
BamfordMike said:
meaning the only differentiation is whatever the treatments go in on top
For clarity, it was this part I was referring to. Nothing goes "in the top", that's all done upstream.
As for the tankers, they do get filled wherever. But some suppliers have their own stock at the distribution point, that is different from others.
It's not all the same.
Edited by BigScotty on Sunday 14th December 08:33
Edited by BigScotty on Sunday 14th December 17:12
BigScotty said:
Nothing goes "in the top", that's all done downstream.
As for the tankers, they do get filled wherever. But some suppliers have their own stock at the distribution point, that is different from others.
It's not all the same.
clearly your "downstream" comment is just posh way of saying "what goes in on top" = "which contains additives" What car 2005. As for the tankers, they do get filled wherever. But some suppliers have their own stock at the distribution point, that is different from others.
It's not all the same.
Edited by BigScotty on Sunday 14th December 08:33
so now at least we agree that literally, tankers get filled up at same fuel depot nozzle and then stuff goes "in on top" and mixed up on the downstream drive to fuel station.
the differentiation is just the additives, which we have all known for a long time. But for clarity, your "nope" statement kind of read to me nope to all tankers filling up same nozzle, which is in the major part for gasoline, is a nope
SAG6Y said:
Right, so from the responses so far, I'm guessing 95 is perfectly fine. Though in the handbook, it does say to use 98. I'm thinking for the extra £5/tank, use super.
you are correct, and in thinking its the best you can do for your car, many would chose the same.if an engine without knock sensors can run 95 but handbook states recommend fill is 97, my guess is the statement to fill higher octane is a)buying a safety margin should anything detonation happen, and octane rating acts as knock sensors) b)marketing, shouldn't luxury sports cars gulp high octane fuel and return the owner a power gain (like the V8 does). Meaning the only justification on engine without knock sensors AND you were seeking the slight gain you would get from 2 ish octane rating / which would roughly equate 3 degrees spark / which would roughly equate 5-7BHP. Is from the warm hug and reassurance that it is supposedly the best you can do for your car, and the marketing of the high end fuel companies has won you over that their fuels contain the best detergents.
my daily hack has 200k miles of the most thrashed, poorly serviced and run on the cheapest fuels money could buy. Has never failed an oxygen sensor, starts cold clean and crisp, doesn't burn oil / smoke and performs as good as the day it was new. What more would i have got for my money had i filled with premium fuel across those 200k miles?
that's for gasoline, I'm pretty sure however that detergents in diesel fuel is different the more money is spent, and the quality fuel is probably better to protect the very expensive pumps and injectors
SAG6Y said:
Right, so from the responses so far, I'm guessing 95 is perfectly fine. Though in the handbook, it does say to use 98. I'm thinking for the extra £5/tank, use super.
Exactly. Pointless using 95, when 98 is available. I have heard detonation in the V12 engines occasionally, but luckily, not being forced induction, you can get away with it. I have however destroyed 2 turbocharged engines with just a fraction of a second of detonation. When you strip the engine, its as if mice have been nibbling at anything metallic, as the combustion process eats the head gasket, head, spark plug, pistons, and top edge of the cylinder wall. All i recovered from both engines, was crank & rods!!
Edited by roughrider on Sunday 14th December 15:45
BamfordMike said:
clearly your "downstream" comment is just posh way of saying "what goes in on top" = "which contains additives" What car 2005.
so now at least we agree that literally, tankers get filled up at same fuel depot nozzle and then stuff goes "in on top" and mixed up on the downstream drive to fuel station.
the differentiation is just the additives, which we have all known for a long time. But for clarity, your "nope" statement kind of read to me nope to all tankers filling up same nozzle, which is in the major part for gasoline, is a nope
Downstream isn't a posh way of saying anything. It means, the additives are added into the manufacturing process earlier. Nothing gets added in the top of the tanker.so now at least we agree that literally, tankers get filled up at same fuel depot nozzle and then stuff goes "in on top" and mixed up on the downstream drive to fuel station.
the differentiation is just the additives, which we have all known for a long time. But for clarity, your "nope" statement kind of read to me nope to all tankers filling up same nozzle, which is in the major part for gasoline, is a nope
The tankers are filled via different nozzles depending on what fuel they're collecting. The tankers themselves are segregated, so they can carry different fuels at the same time.
We never disagreed that the tankers get filled up at the same depot. But, absolutely nothing gets added into the top of the tanker and then gets mixed in on the drive to the fuel station.
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